Spectroscopy and Coherent Control of Two-Level System Defect Ensembles Using a Broadband 3D Waveguide

Abstract

Defects in solid-state materials play a central role in determining coherence, stability, and performance in quantum technologies. Although narrowband techniques can probe specific resonances with high precision, a broadband spectroscopic approach captures the full spectrum of defect properties and dynamics. Two-level system (TLS) defects in amorphous dielectrics are a particularly important example because they are major sources of decoherence and energy loss in superconducting quantum devices. However, accessing and characterizing their collective dynamics remains far more challenging than probing individual TLS defects. Building on our previously developed Broadband Cryogenic Transient Dielectric Spectroscopy (BCTDS) technique, we study the coherent control and time-resolved dynamics of TLS defect ensembles over a wide frequency range of 3-5 GHz without requiring full device fabrication, revealing quantum interference effects, memory-dependent dynamics, and dressed-state evolution within the TLS defect bath. The spectral response reveals distinct V-shaped structures corresponding to the bare eigenmode frequencies. Using these features, we extract a TLS defect spectral density of 84 GHz^-1 for a silicon sample, across a 4.1-4.6 GHz span. Furthermore, we systematically investigate amplitude- and phase-controlled interference fringes for multiple temperatures and inter-pulse delays, providing direct evidence of coherent dynamics and control. A driven minimal spin model with dipole-dipole interactions that qualitatively capture the observed behavior is presented. Our results establish BCTDS as a versatile platform for broadband defect spectroscopy, offering new capabilities for diagnosing and mitigating sources of decoherence, engineering many-body dynamics, and exploring non-equilibrium phenomena in disordered quantum systems.

References in corpus (32)

• Quantum sensing
• Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits
• Scalable Architecture for a Room Temperature Solid-State Quantum Information Processor
• Magnetic field and temperature sensing with atomic-scale spin defects in silicon carbide
• Observation of directly interacting coherent two-level systems in a solid
• Evidence for interacting two-level systems from the 1/f noise of a superconducting resonator
• Determining interface dielectric losses in superconducting coplanar waveguide resonators
• Electric field spectroscopy of material defects in transmon qubits
• Superradiant Hybrid Quantum Devices
• Quantum coherence control at near 1000 K
• Coherent control of a symmetry-engineered multi-qubit dark state in waveguide quantum electrodynamics
• Lifetime and Coherence of Two-Level Defects in a Josephson Junction
• Two-level systems in superconducting quantum devices due to trapped quasiparticles
• Floquet analysis of excitations in materials
• Bulk and Surface Tunneling Hydrogen Defects in Alumina
• Generalized mean-field approach to simulate large dissipative spin ensembles with long range interactions
• Quantum metrology with a single spin-$3/2$ defect in silicon carbide
• Precision measurement of the microwave dielectric loss of sapphire in the quantum regime with parts-per-billion sensitivity
• Dynamics of a two-level system under strong driving: quantum gate optimization based on floquet theory
• Mitigation of interfacial dielectric loss in aluminum-on-silicon superconducting qubits
• Low temperature universality in disordered solids
• Perturbative results on localization for a driven two-level system
• Anisotropic Spin-Acoustic Resonance in Silicon Carbide at Room Temperature
• Low temperature 1/f noise in microwave dielectric constant of amorphous dielectrics in Josephson qubits
• Acoustic spectral hole-burning in a two-level system ensemble
• Hybrid infinite time-evolving block decimation algorithm for long-range multi-dimensional quantum many-body systems
• Pulse excitation to continuous-wave excitation in a low-dimensional interacting quantum system
• Modelling dielectric loss in superconducting resonators: Evidence for interacting atomic two-level systems at the Nb/oxide interface
• Strain-spectroscopy of strongly interacting defects in superconducting qubits
• Floquet engineering using pulse driving in a diamond two-level system under a large-amplitude modulation
• In-situ scanning gate imaging of individual two-level material defects in live superconducting quantum circuits
• Observation and mitigation of microwave echoes from dielectric defects in Josephson traveling wave amplifiers